I'm trying to implement custom cloning in my solution, i followed the instructions as in the documentation, and i encountered a roadblock in the form of this exception : The entity was never added to this ScoreDirector. Maybe that specific instance is not in the return values of the PlanningSolution's entity members. I know that this is not true because before the custom cloning, this exception wasn't thrown.
My planningClone method is setup like this :
#Override
public Solution planningClone() {
Solution clonedSolution = new Solution();
clonedSolution.id = id;
clonedSolution.code = code;
clonedSolution.score = score;
clonedSolution.field1 = field1;
clonedSolution.field2 = field2;
...............
clonedSolution.fieldN = fieldN;
List<PlanningEntity1> clonedPlanningEntity1List= new ArrayList<PlanningEntity1>(planningEntity1List.size());
List<PlanningEntity2> clonedPlanningEntity2List= new ArrayList<PlanningEntity2>(planningEntity1List.size());
for (PlanningEntity1 planningEntity: planningEntity1List) {
clonedPlanningEntity1List.add(planningEntity.clone());
}
for (PlanningEntity2 planningEntity: planningEntity2List) {
clonedPlanningEntity1List.add(planningEntity.clone());
}
clonedSolution.planningEntity1List = clonedPlanningEntity1List;
clonedSolution.planningEntity2List = clonedPlanningEntity2List;
return clonedSolution;
{
The clone method for my planning entities is implemented through the Java interface Cloneable:
protected PlanningEntity clone() {
try {
return (PlanningEntity) super.clone();
} catch (CloneNotSupportedException e) {
e.printStackTrace();
}
return null;
}
Just to be sure, i checked every entity instance and their collections to make sure my cloning was working correctly, and it in fact is.
What step am i missing here?
If there is one planning entity pointing to another planning entity from a different class or maybe pointing to a list, than the cloning process needs to take care of the references for those planning entities so they point to the cloned objects.This is something that the default cloning process is doing without a problem, and thus leaving the solution in a consistent state. It even updates the Lists of planning entity instances in the parent planning entities correctly (covered by the method "cloneCollectionsElementIfNeeded" from the class "FieldAccessingSolutionCloner" from the OptaPlanner core).
So for example if we have the next two planning entity classes
#PlanningEntity
public class ParentPlanningEntityClass{
List<ChildPlanningEntityClass> childPlanningEntityClassList;
}
#PlanningEntity
public class ChildPlanningEntityClass{
ParentPlanningEntityClass parentPlanningEntityClass;
}
The "parentPlanningEntityClass" variable needs to be set to point to the cloned object. When it comes to the list "childPlanningEntityClassList" it first needs to be created from scratch with "new ArrayList();" so that both the working and new best solution (the one that is currently getting cloned) don't point to the same list. At the end the newly created list needs to be filled with the cloned objects.
Related
I am implementing an algorithm similar to the NurseRoster one in OptaPlanner. I need to implement a rule in drools that check if the Employee cannot work more days than the number of days in his contract. Since i couldn't figure out how to make this in drools, i decided to write it as a method in a class, and then use it in drools to check if the constraint has been broken. Since i needed a List of ShiftAssignments in the Employee class, i needed to use an #InverseRelationShadowVariable that updated that list automatically an Employee got assigned to a Shift. Since my Employee now has to be a PlanningEntity, the error The entity was never added to this ScoreDirector appeared. I believe the error is caused by my ShiftAssignment entity, which has a #ValueRangeProvider of employees that can work in that Shift. I think this is due to the fact that ScoreDirector.beforeEntityAdded and ScoreDirector.afterEntityAdded were never called, hence the error. For some reason when i removed that range provider from ShiftAssignment and put it on NurseRoster which is the #PlanningSolution, it worked.
Here is the code:
Employee:
#InverseRelationShadowVariable(sourceVariableName = "employee")
public List<ShiftAssignment> getEmployeeAssignedToShiftAssignments() {
return employeeAssignedToShiftAssignments;
}
ShiftAssignment:
#PlanningVariable(valueRangeProviderRefs = {
"employeeRange" }, strengthComparatorClass = EmployeeStrengthComparator.class,nullable = true)
public Employee getEmployee() {
return employee;
}
// the value range for this planning entity
#ValueRangeProvider(id = "employeeRange")
public List<Employee> getPossibleEmployees() {
return getShift().getEmployeesThatCanWorkThisShift();
}
NurseRoster:
#ValueRangeProvider(id = "employeeRange")
#PlanningEntityCollectionProperty
public List<Employee> getEmployeeList() {
return employeeList;
}
And this is the method i use to update that listOfEmployeesThatCanWorkThisShift:
public static void checkIfAnEmployeeCanBelongInGivenShiftAssignmentValueRange(NurseRoster nurseRoster) {
List<Shift> shiftList = nurseRoster.getShiftList();
List<Employee> employeeList = nurseRoster.getEmployeeList();
for (Shift shift : shiftList) {
List<Employee> employeesThatCanWorkThisShift = new ArrayList<>();
String shiftDate = shift.getShiftDate().getDateString();
ShiftTypeDefinition shiftTypeDefinitionForShift = shift.getShiftType().getShiftTypeDefinition();
for (Employee employee : employeeList) {
AgentDailySettings agentDailySetting = SearchThroughSolution.findAgentDailySetting(employee, shiftDate);
List<ShiftTypeDefinition> shiftTypeDefinitions = agentDailySetting.getShiftTypeDefinitions();
if (shiftTypeDefinitions.contains(shiftTypeDefinitionForShift)) {
employeesThatCanWorkThisShift.add(employee);
}
}
shift.setEmployeesThatCanWorkThisShift(employeesThatCanWorkThisShift);
}
}
And the rule that i use:
rule "maxDaysInPeriod"
when
$shiftAssignment : ShiftAssignment(employee != null)
then
int differentDaysInPeriod = MethodsUsedInScoreCalculation.employeeMaxDaysPerPeriod($shiftAssignment.getEmployee());
int maxDaysInPeriod = $shiftAssignment.getEmployee().getAgentPeriodSettings().getMaxDaysInPeriod();
if(differentDaysInPeriod > maxDaysInPeriod)
{
scoreHolder.addHardConstraintMatch(kcontext, differentDaysInPeriod - maxDaysInPeriod);
}
end
How can i fix this error?
This has definitely something to do with the solution cloning that is happening when a "new best solution" is created.
I encountered the same error when i implemented custom solution cloning. In my project i have multiple planning entity classes and all of them have references to each other (either a single value or a List). So when solution cloning is happening the references need to be updated so they can point to the cloned values. This is something that the default cloning process is doing without a problem, and thus leaving the solution in a consistent state. It even updates the Lists of planning entity instances in the parent planning entities correctly (covered by the method "cloneCollectionsElementIfNeeded" from the class "FieldAccessingSolutionCloner" from the OptaPlanner core).
Just a demonstration what i have when it comes to the planning entity classes:
#PlanningEntity
public class ParentPlanningEntityClass{
List<ChildPlanningEntityClass> childPlanningEntityClassList;
}
#PlanningEntity
public class ChildPlanningEntityClass{
ParentPlanningEntityClass parentPlanningEntityClass;
}
At first i did not update any of the references and got the error even for "ChildPlanningEntityClass". Then i have written the code that updates the references. When it comes to the planning entity instances that were coming from the class "ChildPlanningEntityClass" everything was okay at this point because they were pointing to the cloned object. What i did wrong in the "ParentPlanningEntityClass" case was that i did not create the "childPlanningEntityClassList" list from scratch with "new ArrayList();", but instead i just updated the elements of the list (using the "set" method) to point at the cloned instances of the "ChildPlanningEntityClass" class. When creating a "new ArrayList();", filling the elements to point to the cloned objects and setting the "childPlanningEntityClassList" list everything was consistent (tested with FULL_ASSERT).
So just connecting it to my issue maybe the list "employeeAssignedToShiftAssignments" is not created from scratch with "new ArrayList();" and elements instead just get added or removed from the list. So what could happen (if the list is not created from scratch) here is that both the working and the new best solution (the clone) will point to the same list and when the working solution would continue to change this list it would corrupt the best solution.
I've written an Xtext-based plugin for some language. I'm now interested in creating a new independent view (as a separate plugin, though it requires my first plugin), which will interact with the currently-active DSL document - and specifically, interact with the model Xtext parsed (I think it's called the Ecore model?). How do I approach this?
I saw I can get an instance of XtextEditor if I do something like this when initializing my view:
getSite().getPage().addPartListener(new MyListener());
And then, in MyListener, override partActivated and partInputChanged to get an IWorkbenchPartReference, which is a reference to the XtextEditor. But what do I do from here? Is this even the right approach to this problem? Should I instead use some notification functionality from the Xtext side?
Found it out! First, you need an actual document:
IXtextDocument doc = editor.getDocument();
Then, if you want to access the model:
doc.modify(new IUnitOfWork.Void<XtextResource>() { // Can also use just IUnitOfWork
#Override public void process(XtextResource state) throws Exception {
...
}
});
And if you want to get live updates whenever it changes:
doc.addModelListener(new IXtextModelListener() {
#Override public void modelChanged(XtextResource resource) {
for (EObject model : resource.getContent()) {
...
}
}
});
Being rather new to MVC 3 and EF, I'm trying to understand the best architectural approach to developing an application for my company. The application will be a large-scale application that potentially handles hundreds of users at the same time, so I want to make sure I understand and am following proper procedures. So far, I've determined that a simple repository pattern (such as Controller -> Repository -> EF) approach is the best and easiest to implement, but I'm not sure if that is definitely the best way to do things. The application will basically return data that is shown to a user in a devexpress grid and they can modify this data/add to it etc.
I found this article and it is rather confusing for me at this time, so I'm wondering if there is any reason to attempt to work with a disconnected EF and why you would even want to do so: http://www.codeproject.com/Articles/81543/Finally-Entity-Framework-working-in-fully-disconne?msg=3717432#xx3717432xx
So to summarize my question(s):
Is the code below acceptable?
Should it work fine for a large-scale MVC application?
Is there a better way?
Will unnecessary connections to SQL remain open from EF? (SQL Profiler makes it look like it stays open a while even after the using statement has exited)
Is the disconnected framework idea a better one and why would you even want to do that? I don't believe we'll need to track data across tiers ...
Note: The repository implements IDisposable and has the dispose method listed below. It creates a new instance of the entity context in the repository constructor.
Example Usage:
Controller (LogOn using Custom Membership Provider):
if (MembershipService.ValidateUser(model.UserName, model.Password))
{
User newUser = new User();
using (AccountRepository repo = new AccountRepository())
{
newUser = repo.GetUser(model.UserName);
...
}
}
Membership Provider ValidateUser:
public override bool ValidateUser(string username, string password)
{
using (AccountRepository repo = new AccountRepository())
{
try
{
if (string.IsNullOrEmpty(password.Trim()) || string.IsNullOrEmpty(username.Trim()))
return false;
string hash = FormsAuthentication.HashPasswordForStoringInConfigFile(password.Trim(), "md5");
bool exists = false;
exists = repo.UserExists(username, hash);
return exists;
}catch{
return false;
}
}
}
Account Repository Methods for GetUser & UserExists:
Get User:
public User GetUser(string userName)
{
try
{
return entities.Users.SingleOrDefault(user => user.UserName == userName);
}
catch (Exception Ex)
{
throw new Exception("An error occurred: " + Ex.Message);
}
}
User Exists:
public bool UserExists(string userName, string userPassword)
{
if (userName == "" || userPassword == "")
throw new ArgumentException(InvalidUsernamePassword);
try
{
bool exists = (entities.Users.SingleOrDefault(u => u.UserName == userName && u.Password == userPassword) != null);
return exists;
}
catch (Exception Ex)
{
throw new Exception("An error occurred: " + Ex.Message);
}
}
Repository Snippets (Constructor, Dispose etc):
public class AccountRepository : IDisposable
{
private DbContext entities;
public AccountRepository()
{
entities = new DbContext();
}
...
public void Dispose()
{
entities.Dispose();
}
}
What's acceptable is pretty subjective, but if you want to do proper data access I suggest you do NOT use the repository pattern, as it breaks down as your application gets more complex.
The biggest reason is minimizing database access. So for example look at your repository and notice the GetUser() method. Now take a step back from the code and think about how your application is going to be used. Now think about how often you are going to request data from the user table without any additional data. The answer is almost always going to be "rarely" unless you are creating a basic data entry application.
You say it your application will show a lot of grids. What data is in that Grid? I'm assuming (without knowing your application domain) that the grids will combine user data with other information that's relevant for that user. If that's the case, how do you do it with your repositories?
One way is to call on each repository's method individually, like so:
var user = userRepository.GetUser("KallDrexx");
var companies = companyRepository.GetCompaniesForUser(user.Id);
This now means you have 2 database calls for what really should be just one. As your screens get more and more complex, this will cause the number of database hits to increase and increase, and if your application gets significant traffic this will cause performance issues. The only real way to do this in the repository pattern is to add special methods to your repositories to do that specific query, like:
public class UserRepository
{
public User GetUser(string userName)
{
// GetUser code
}
public User GetUserWithCompanies(string userName)
{
// query code here
}
}
So now what happens if you need users and say their contact data in one query. Now you have to add another method to your user repository. Now say you need to do another query that also returns the number of clients each company has, so you need to add yet another method (or add an optional parameter). Now say you want to add a query that returns all companies and what users they contain. Now you need a new query method but then comes the question of do you put that in the User repository or the Company repository? How do you keep track of which one it's in and make it simple to choose between GetUserWithCompany and GetCompanyWithUsers when you need it later?
Everything gets very complex from that point on, and it's those situations that have made me drop the repository pattern. What I do now for data access is I create individual query and command classes, each class represents 1 (and only 1) query or data update command to the database. Each query class returns a view model that only contains the data I need for one specific user usage scenario. There are other data access patterns that will work too (specification pattern, some good devs even say you should just do your data access in your controllers since EF is your data access layer).
The key to doing data access successfully is good planning. Do you know what your screens are going to look like? Do you know how users are going to use your system? Do you know all the data that is actually going to be on each screen? If the answer to any of these is no, then you need to take a step back and forget about the data layer, because the data layer is (or should be for a good application) determined based on how the application is actually going to be used, the UI and the screens should not be dependent on how the data layer was designed. If you don't take your UI needs and user usage scenarios into account when developing the data access, your application will not scale well and will not be performant. Sometimes that's not an issue if you don't plan on your site being big, but it never hurts to keep those things in mind.
No matter what you do, you may consider moving instantiation and disposing of your context to your controller like this:
public class MyController : Controller
{
private Entities context = new Entities();
...
public override void Dispose()
{
context.Dispose();
}
}
You can then pass that context into any method that needs it without duplicating the overhead of creating it.
I disagree that the repository pattern is necessarily bad for the same reason. You create multiple classes to break up your code to make it manageable and still reuse the same context. That could look something like this:
repository.Users.GetUser(userName);
In this case "Users" is a lazy loaded instance of your user repository class which reuses the context from your repository. So the code for that Users property in your repository would look something like this:
private UserRepository users;
public UserRepository Users
{
get
{
If (users == null)
{
users = new UserRepository(this);
}
return users;
}
}
You can then expose your context to these other lazy loaded classes via a property.
I don't think this necessarily conflicts with KallDrexx's pattern. His method simply flips this so instead of
repository.Users.GetUser(userName);
You would have something like
UserQuery query = new UserQuery(repository.Users);
This then becomes an issue of syntax. Do you want this:
repository.Area.Query(value1, value2, ...);
Or this:
AreaQuery query = new AreaQuery { Property1 = value1, ... };
The latter actually works nicer with model binding but obviously is more verbose when you actually have to code it.
Best advice KallDrexx gave is to just put your code I your actions and then figure it out. If you are doing simple CRUD, then let MVC instantiate and populate your model, then all you have to do is attach and save. If you find you can reuse code, move it to where it can be reused. If your application starts getting too complicated, try some of these recommendations until you find what works for you.
The entities and mappings I'm talking about in this question can be found here :)
Here is the context:
I have a parent view-model which helps to manage some entities, and which has its own session.
From this VM, I open another view-model (with its own session too), do some changements to the entity (add and/or remove children), and when I validate the changements, I commit the session and warns the first view-model to refresh the display:
public void Validate()
{
using (var tx = Session.BeginTransaction())
{
try
{
SelectedTeam.ClearRoster();
foreach (var teamPlayer in TeamPlayers)
SelectedTeam.AddPlayer(teamPlayer);
teamsRepository.SaveOrUpdate(SelectedTeam);
tx.Commit();
}
catch (Exception ex)
{
tx.Rollback();
}
finally
{
if (tx.WasCommitted)
ServiceLocator.Current.GetInstance<Mediator>().NotifyColleagues(MediatorMessages.DisplayEntityInfos, SelectedTeam.Id);
}
}
}
Here is the faulted method of the parent VM:
public void RefreshEntitiesListAndDisplayEntityInfos(int selectedEntityId)
{
TEntity entity = entitiesRepository.Load(selectedEntityId);
Session.Refresh(entity);
//...
}
The exception is thrown at the Refresh line:
NHibernate.UnresolvableObjectException
And the message is:
No row with the given identifier exists[Emidee.CommonEntities.PlayerInTeam#3
I can open and change the entity multiple times, but it seems that the exception is thrown when I delete a children, then add another one, and finally delete another one.
After some readings on the web, it seems that's because when I refresh the entity, and because I changed the HasMany relationship (because I have deleted a player for example), NH tries to reload the deleted row.
I've tried to add a NotFound.Ignore statement on the HasMany in my mappings, I've tried to force a new query to the DB instead of a Load, but I still get this exception.
Does someone know how I could fix that?
Thanks in advance
Mike
This is a known behavior when refreshing objects with modified collections.
To force reload, change your method to do session.Evict with the entity as a parameter. This is the code we use in our base model class:
public T ReGet<T>(T entity) where T : IEntity
{
var id = entity.Id;
Session.Evict(entity);
return Session.Get<T>(id);
}
Well, I've just spotted the problem.
To update the players list of the team, I used to clear the list, and add the new players, before updating the entity.
Now, I update the list by removing and adding only the players who have been moved by the user, and I don't have any problems at all now.
That's weird. I don't know what was wrong before, but as least that works now.
Updated: 09/02/2009 - Revised question, provided better examples, added bounty.
Hi,
I'm building a PHP application using the data mapper pattern between the database and the entities (domain objects). My question is:
What is the best way to encapsulate a commonly performed task?
For example, one common task is retrieving one or more site entities from the site mapper, and their associated (home) page entities from the page mapper. At present, I would do that like this:
$siteMapper = new Site_Mapper();
$site = $siteMapper->findByid(1);
$pageMapper = new Page_Mapper();
$site->addPage($pageMapper->findHome($site->getId()));
Now that's a fairly trivial example, but it gets more complicated in reality, as each site also has an associated locale, and the page actually has multiple revisions (although for the purposes of this task I'd only be interested in the most recent one).
I'm going to need to do this (get the site and associated home page, locale etc.) in multiple places within my application, and I cant think of the best way/place to encapsulate this task, so that I don't have to repeat it all over the place. Ideally I'd like to end up with something like this:
$someObject = new SomeClass();
$site = $someObject->someMethod(1); // or
$sites = $someObject->someOtherMethod();
Where the resulting site entities already have their associated entities created and ready for use.
The same problem occurs when saving these objects back. Say I have a site entity and associated home page entity, and they've both been modified, I have to do something like this:
$siteMapper->save($site);
$pageMapper->save($site->getHomePage());
Again, trivial, but this example is simplified. Duplication of code still applies.
In my mind it makes sense to have some sort of central object that could take care of:
Retrieving a site (or sites) and all nessessary associated entities
Creating new site entities with new associated entities
Taking a site (or sites) and saving it and all associated entities (if they've changed)
So back to my question, what should this object be?
The existing mapper object?
Something based on the repository pattern?*
Something based on the unit of work patten?*
Something else?
* I don't fully understand either of these, as you can probably guess.
Is there a standard way to approach this problem, and could someone provide a short description of how they'd implement it? I'm not looking for anyone to provide a fully working implementation, just the theory.
Thanks,
Jack
Using the repository/service pattern, your Repository classes would provide a simple CRUD interface for each of your entities, then the Service classes would be an additional layer that performs additional logic like attaching entity dependencies. The rest of your app then only utilizes the Services. Your example might look like this:
$site = $siteService->getSiteById(1); // or
$sites = $siteService->getAllSites();
Then inside the SiteService class you would have something like this:
function getSiteById($id) {
$site = $siteRepository->getSiteById($id);
foreach ($pageRepository->getPagesBySiteId($site->id) as $page)
{
$site->pages[] = $page;
}
return $site;
}
I don't know PHP that well so please excuse if there is something wrong syntactically.
[Edit: this entry attempts to address the fact that it is oftentimes easier to write custom code to directly deal with a situation than it is to try to fit the problem into a pattern.]
Patterns are nice in concept, but they don't always "map". After years of high end PHP development, we have settled on a very direct way of handling such matters. Consider this:
File: Site.php
class Site
{
public static function Select($ID)
{
//Ensure current user has access to ID
//Lookup and return data
}
public static function Insert($aData)
{
//Validate $aData
//In the event of errors, raise a ValidationError($ErrorList)
//Do whatever it is you are doing
//Return new ID
}
public static function Update($ID, $aData)
{
//Validate $aData
//In the event of errors, raise a ValidationError($ErrorList)
//Update necessary fields
}
Then, in order to call it (from anywhere), just run:
$aData = Site::Select(123);
Site::Update(123, array('FirstName' => 'New First Name'));
$ID = Site::Insert(array(...))
One thing to keep in mind about OO programming and PHP... PHP does not keep "state" between requests, so creating an object instance just to have it immediately destroyed does not often make sense.
I'd probably start by extracting the common task to a helper method somewhere, then waiting to see what the design calls for. It feels like it's too early to tell.
What would you name this method ? The name usually hints at where the method belongs.
class Page {
public $id, $title, $url;
public function __construct($id=false) {
$this->id = $id;
}
public function save() {
// ...
}
}
class Site {
public $id = '';
public $pages = array();
function __construct($id) {
$this->id = $id;
foreach ($this->getPages() as $page_id) {
$this->pages[] = new Page($page_id);
}
}
private function getPages() {
// ...
}
public function addPage($url) {
$page = ($this->pages[] = new Page());
$page->url = $url;
return $page;
}
public function save() {
foreach ($this->pages as $page) {
$page->save();
}
// ..
}
}
$site = new Site($id);
$page = $site->addPage('/');
$page->title = 'Home';
$site->save();
Make your Site object an Aggregate Root to encapsulate the complex association and ensure consistency.
Then create a SiteRepository that has the responsibility of retrieving the Site aggregate and populating its children (including all Pages).
You will not need a separate PageRepository (assuming that you don't make Page a separate Aggregate Root), and your SiteRepository should have the responsibility of retrieving the Page objects as well (in your case by using your existing Mappers).
So:
$siteRepository = new SiteRepository($myDbConfig);
$site = $siteRepository->findById(1); // will have Page children attached
And then the findById method would be responsible for also finding all Page children of the Site. This will have a similar structure to the answer CodeMonkey1 gave, however I believe you will benefit more by using the Aggregate and Repository patterns, rather than creating a specific Service for this task. Any other retrieval/querying/updating of the Site aggregate, including any of its child objects, would be done through the same SiteRepository.
Edit: Here's a short DDD Guide to help you with the terminology, although I'd really recommend reading Evans if you want the whole picture.